}
public ExcelReader createExcelReader(Class<? extends ExcelReader> clazz, String... sheets){
ExcelReader excelReader = null;
if(clazz == null)
excelReader = new DefaultExcelReader();
else{
try {
excelReader = (ExcelReader)clazz.newInstance();
} catch (InstantiationException e) {
throw new RuntimeException("Initiate ExcelReader[" + clazz + "] failure");